February 4, 2016

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Professor's related study discovers technology to remove problematic agent from wastewater

MILWAUKEE — In a study recently published in the journal Environmental Science and Technology, Marquette University engineering professor Dr. Patrick McNamara, along with colleagues Dr. Daniel Zitomer, director of Marquette's Water Quality Center, and Krassimira Hristova, assistant professor of biology, found that an antimicrobial agent commonly found in hard soaps is linked to antibiotic resistance, a growing public health concern.

In a separate but related study funded by the National Science Foundation's Water Equipment and Policy center and published in the journal Environmental Science: Water Research and Technology, the assistant professor of civil and environmental engineering discovered that a technology called pyrolysis can be used to remove the agent from biosolids. This work was done in collaboration with Zitomer and Dr. Todd Miller, assistant professor of environmental health sciences at the University of Wisconsin-Milwaukee's Zilber School of Public Health.

The chemical, triclocarban (TCC), passes through the anaerobic digesters that sewage treatment plants use to treat waste, and the study found that, at environmental levels, TCC selects for a multidrug resistance gene.

"Antibiotic resistance is a serious health threat," McNamara said. "These genes are what make superbugs super.

"TCC is found in even higher abundance in wastewater biosolids than a similar agent, triclosan, yet significantly more research has been done on triclosan," he added. "We're just starting to learn more about what TCC does in the environment."

According to McNamara, it is unlikely that TCC will be regulated, but consumer awareness can help cut down amount of the chemical sent to treatment plants. Further, his second study demonstrates that a thermal decomposition process called pyrolysis, which is used widely in the chemical industry, can be used to eliminate TCC from waste.

Pyrolysis is the heating of biomass in the absence of oxygen, unlike the more common combustion, which is the heating of biomass in the presence of oxygen. During combustion, the products are carbon dioxide and water. Since pyrolysis happens in the absence of oxygen, the gas products are higher energy products such as hydrogen, methane and carbon monoxide. Pyrolysis can produce a valuable solid product, biochar, which is void of TCC and also produces a gas that has high energy content.

For manuscripts or to interview McNamara, please contact Christopher Stolarski, senior communication strategist, at christopher.stolarski@marquette.edu.